Can I sue welding cable as a service feeder cable from Genset to Transfer Switch (400amp, 120/208v, 3phase)
Depends on how the cable is listed, typically lower cost welding cable is labeled as "Welding Cable", where as some carry dual listing. It should be noted that the finer strand sizes require specialized terminations and connectors.
As always, it's best to consult your local AHJ for their requirements.
To be a bit more specific, the cable has to be listed or otherwise recognized type for how it is to be used under the NEC. As cable, it must be recognized in 400.4. As single conductor, 310.104.
No, it cannot be installed for that purpose. The generator feeder conductors will have to be sized in accordance with 445.13 and will be required to be installed in accordance with Article 300 and the code articles for the installed Chapter 3 wiring methods. Welding cables are listed for use with welders and the NEC requires it to be installed in a dedicated cable tray as required in Part IV of Article 630. Additionally, the generator control conductor will have to be installed in accordance with Article 725 as they could be either Class 1 or Class 2 control circuits. Be sure to read the generator and transfer equipment manufacturers's installation instructions, as the manufacturer have have additional installation requirements for the generator feeder and control conductors.
"No, it cannot be installed for that purpose. ..."
Some welding cable is dual listed and can be, as noted above by Chris Carlson and supplemented by me.
Not according to UL per the UL 1276 Outline for Investigation for Welding Cable. The UL document covers welding cable, which is a single-conductor cable intended for use in the secondary circuit of electric welders in accordance with Article 630, Part IV of ANSI/NFPA 70, "National Electrical Code." The conductors are flexible-stranded copper, 8 AWG through 500 kcmil, the individual strands of which are 34 through 30 AWG.
110.3(B) requires the welding cable to be installed in accordance with its listing instructions, which does not permit its use with generators or transfer equipment. If a dual listing existed, it would be part of the Scope of the UL document and the cable would be listed for the intended use. Additionally, if the cable would be recognized as a flexible cord or cable in Article 400, that would make it electrical equipment and therefore not a Chapter 3 wiring method.
But all you are looking at is the UL standard for welding cable. Does it say welding cable cannot be listed as another type of cable or conductor?
General Cable's Super Vu-Tron® Welding Cable is an example. It is dual listed as RHH RHW and also marked for cable tray use, which falls under Article 336 and/or Article 392... so it can be a Chapter 3 wiring method.
The UL 1276 Outline requires the that the product identity has the following:
The following product identity appears on the product:
The General Cable UL certification for welding cable can be found on the UL Online Certification Directory, ZMAY.E91935 Welding Cable is the file number for General Cable.
From the General Cable website, General Cable Super Vu-Tron welding cable is ideal for use in secondary voltage resistance welding leads and power supply applications not exceeding 600 volts AC. Sizes 1/0 and larger are suitable for permanent wiring in conduit or tray of 600 V power supplies, hoists, cranes or other applications where flexible power leads must be installed in conduit, raceways or trays. The only electrical equipment that requires flexible power connections are in Articles 610 and 620 and those articles allow listed flexible cables to be installed as a wiring method, but those Articles have their own restrictions as well. Remember Chapters 5, 6, and 7 of the NEC are permitted to modify the requirements in Chapters 1-7.
However, Articles 610, 620, and 630 do not cover generators or transfer equipment so they do not modify any of the NEC requirements for generators or transfer equipment. Articles 445, 700, 701, and 702 would have purview over the generator installation. Generators and transfer switches do not require flexible power leads, and the terminals in the equipment are not listed for the termination of finely stranded conductors. It will not be possible to achieve the proper torque values required in 110.14(D) on the terminations in the generator or transfer switch if the wrong type of conductor is utilized. As I stated in my previous comment, 110.3(B) also applies to the generator and transfer equipment, as listed and labeled equipment shall be installed in accordance with the instructions included with the listing and labeling, which would include the manufacturers installation instructions.
Article 336 covers Type TC, TC-ER, and TC-ER-JP cables, just because a cable can be installed within a cable tray (Art. 392) it does not make the cable a listed Type TC cable, so Article 336 would not have purview over a welding cable installed in a dedicated cable tray as required by 630.42(A), (B), and (C). If this would of been a generator installation for a one or two family dwelling unit, the 2017 NEC permits the use of Type TC-ER-JP cable, and the exception in 336.10(9) is specific to generator and transfer equipment installation.
It is not the welding cable listing which is of concern. In this matter, it is the dual listing, i.e. having a listing as more than one type of cable or conductor. The following jacket marking appears on General Cable [Carol] Super Vu-Tron® Welding Cable sizes 1/0 - 4/0 AWG:
CAROL SUPER VU-TRON WELDING CABLE (SIZE) EXTRA FLEXIBLE (UL) 600 VOLT (-50 to +90C) OIL RESISTANT P-123-141 MSHA --- CSA 90C ARC WELDING CABLE FT-1 --- TYPE RHH OR RHW (UL) 600V FOR CT USE
Please look up what this means in the UL Wire and Cable Marking and Application Guide.
Also view the data sheet at http://gccu.generalcable.com/elearncordcertgccweb/sv_wld.pdf
Regarding your point about terminations, I direct you to two industry published articles on the matter:
UL's Tools and Tips for Assessing Compliance with Fine Stranded Cable Termination Requirements
NEMA's Bulletin 105: Fine-Stranded Cable Connections
As previously stated in my prior comments, the lugs in the generator and the transfer equipment have to be listed for use with finely stranded conductors. The document that you reference states the same. The generators and transfer equipment that my company manufactures are not listed for use with finely stranded conductors. I work within the Engineering and Technical divisions of my company and I am a certified electrical inspector. If I would come across a generator and transfer switch wired with welding cable, the only way I would approve such an insulation would be to have signed and stamped letters from the Professional Engineers of the manufacturer of the generator and the switch, and I would require UL to perform a field evaluation on the installation. The General Cable listed welding cable spec sheet has the exact same information I referenced in a previous comment. UL evaluates that cable as a welding cable and it is listed as such and Part IV of Article 630is the only NEC code article that references the installation requirements for welding cable.
The part you are definitely missing is the dual listing of the mentioned cable (as an example; there are others). You are hung up on it being listed as welding cable. Forget about that. It is listed as RHH and RHW. Provided each conductor is properly terminated, it can be used in any application in which RHH or RHW is permitted... including as single conductors in a cable tray application.
Also, you apparently missed the part in the NEMA Bulletin about using pin connectors listed for fine-stranded conductors. FWIW, there are other methods to transition from fine-stranded to Class B or C stranded conductors prior to terminating on [your] equipment. In fact, if the reference cable/conductor is run in cable tray, the installer can transition to a manufacturer's approved cable/conductor without an enclosure.
Joseph, why don't you reach out to the NFPA Technical Staff and UL to see if they are in agreement with your positions, and if they are, I'll stand corrected. A listed welding cable with a dual insulation rating is still identified on the cable jacket as a welding cable, as that is a listing requirement for that type of cable. The issue is what is in the scope of the UL Outline for Investigation for that cable. 110.3(B) requires that listed products be installed in accordance with the listing, and the UL scope only mentions the installation in accordance with Part IV of Article 630. The big question that needs to be asked of UL is the following, Does UL evaluate and recognize welding cable as a Chapter 3 wiring method, or is is only evaluated as a welding cable?
I already know the position of both. It is stated in the UL Wire and Cable Marking and Application Guide (link provided above), page 9, section 5, second paragraph.
I also asked UL.
Welding cable is UL Listed under the product category Welding Cable (ZMAY). The UL Guide Information for ZMAY states: “This category covers welding cable, which is a single-conductor cable intended for use in the secondary circuit of electric welders in accordance with Article 630, Part IV of ANSI/NFPA 70, "National Electrical Code."
Welding cable by itself is not recognized by the NEC as conductor for general wiring per Article 310 and doesn’t qualify as a Chapter 3 wiring method.
If the cable is dually rated and marked as RHH/RHW on the insulation, then it could be considered as RHH/RHW insulated conductors and used as permitted in the NEC for RHH/RHW conductors. The RHH/RHW is only in the 1/0-4/0 range.
The ampacity of a 4/0 is 230 Amps at 75C, that would limit the generator size to no larger than 60- 65 kW depending on the manufacturer. Most manufacturer have lugs rated at 75C with Class B stranded conductors. That's an awfully undersized generator to install on a 400 Amp ATS. Again, there needs to be a listed terminal or transition for the connection of a finely stranded Class C conductors to the Class B lugs in the generator and ATS that won't violate the listings of those pieces of equipment, and any manufacturer's installation instructions and equipment factory warranties.
So I stand partially corrected, a dual listed welding cable could be used under the following conditions;
listed terminations are used to transition and terminate a Class C conductor to a Class B terminal,
the generators nameplate current rating is 230 A or less,
the generator an ATS manufacturer installation instructions permit it
and all applicable NEC codes are also met.
"The ampacity of a 4/0 is 230 Amps at 75C.... That's an awfully undersized generator to install on a 400 Amp ATS."
Parallel conductors (2 sets 4/0) will get you 460A @ 75°C.
And if you want to get real progressive, run one set as 4/0 RHH in cable tray and use Table 310.15(B)(17) for ampacity determination... 405A @ 90°C. Transition in the tray without enclosure using 90°C-rated connectors to 600kcmil [420A @ 75°C under Table 310.15(B)(16)] and proceed to final terminations on equipment. 400A circuit and all completely compliant.
Could also do the preceding as RHW with 400A OCPD but that limits the circuit to 360A calculated load.
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